Technical Field
The present invention relates to the field of carbon nanotube thin membrane preparation technologies, and specifically, relates to a method for preparing a highly vertically oriented carbon nanotube thin membrane provided with an opening.
Related Art
The carbon nanotube is a novel carbon structure that is not found until 1991; it is an ideal structure formed mainly based on sp2 hybridization in carbon atoms and mixed with sp3 hybridization. A carbon nanotube may be considered as a seamless and hollow tube body which is rolled up by sheet-like graphene. A structure of the carbon nanotube is a complete graphene gird. Therefore, theoretical strength of the carbon nanotube is close to strength of the carbon-carbon bond, and strength of the carbon nanotube is theoretically predicted to be about 100 times of that of steel, but a density is only ⅙ of that of steel. Moreover, the carbon nanotube has high damage resistant and distortion resistant capabilities, and therefore, the carbon nanotube is referred to as a super fiber. The carbon nanotube has an extremely large specific surface area which may be 1315 m2/g at maximum, and is also considered to be an ideal novel hydrogen storage material because of its excellent adsorption properties. When the carbon nanotube serves as a catalyst carrier, a rate for a substance to pass through is thousands of times of that of a common catalyst, so that a chemical reaction rate can be significantly changed. For gas storage and filling of the carbon nanotube, the top of the carbon nanotubes needs to be opened. Carbon nanotubes provided with opening may be filled with metal, oxides, and the like, so as to obtain other nano materials needed by people. Meanwhile, the carbon nanotubes provided with opening at the top portion are also very helpful for improving beam emission in the low-conductive electric field and for grafting functional macromolecules.
Carbon nanotubes gradually become a hot spot researched in the field of nano materials because of their features such as a large superficial area, good heat conductivity and electrical conductivity, high chemical stability, and high mechanical strength. However, carbon nanotubes are Nano materials, and have higher actual application value if the carbon nanotubes are made into macro bodies such as carbon nanotube thin membrane provided with opening. For the carbon nanotube thin membrane prepared in the prior art, most carbon nanotubes are disorderly arranged, and the ports are closed and contain catalyst impurities. As a result, the applications of the carbon nanotubes are greatly limited. When the carbon nanotube array is etched by using argon-oxygen plasma, the top portion of the carbon nanotubes may be bombarded by using high energy of heavy ion argon, and oxygen plasma may serve as a bombarding ion and may also remove amorphous carbon and catalyst particles after argon bombardment. When carbon nanotubes grow into a membrane, carbon nanotubes interact with each other because of van der Waals force, and when the growth density reaches a particular value, the carbon nanotubes are forced to grow uniformly along a vertical direction to form a self-supporting membrane-like macro body because of the limitation of growing space. This type of highly consistent and vertically oriented carbon nanotube thin membranes provided with openings are consistent in direction and are orderly arranged, and each carbon nanotube has a good opening performance. Moreover, compared with carbon nanotube thin membranes which grow and are arranged disorderly, this type of carbon nanotube thin membranes further have a larger specific surface area, and higher electrical conduction and heat conduction capabilities. When this type of carbon nanotube thin membranes serve as heat conduction and electrical conduction and membrane filtering materials and catalyst carriers, mass transfer and heat transfer efficiency of the substances is also greatly improved. Therefore, preparing a highly vertically oriented and highly densified carbon nanotube thin membrane provided with opening is an effective way to improve actual application value of the carbon nanotubes.